In vibration testing, including modal analysis, a large amount of hardware equipment would be required for the large scale model testing when traditional vibration sensors are used. Further time and efforts of a group of engineers would be significant too in order to carry out the tests over hundreds of measurement points on the device under test.
Since a few decades ago, DIC technology emerged with the development of the high speed camera. In recent decades, the advances of 3D stereo camera and associated DIC methods make it possible to measure the 3-dimensional vibration deformation of the device under test. This technology results in the full field measurement of the device under test, and which also can be done with significant less time and effort.
In a conventional DIC based vibration testing system, a shaker table is used to drive the device under test, while one or more cameras image the device under test being excited. Because there is typically no synchronization between the vibration of the shaker table and the exposure trigger for the cameras, expensive high-speed cameras need to be used to ensure an image sampling rate that is at least twice the vibration frequency of the device under test. This is the normal sampling mode for image acquisition in such systems.
As a possible cheaper alternative, one might contemplate use of low-cost, but also low-speed, cameras with some kind of under-sampling technique by means of synchronized triggering of such cameras. However, the existence of jitter (time deviations) in either the trigger signal itself, or more commonly in the cameras' response, severely limits the potential accuracy of such a scheme. Any random deviations in the cameras' frame capture times will result in errors during subsequent processing to reconstruct a correct sequence of image frames.